Christopher Nolan’s The Dark Knight is widely considered the best superhero movie ever made, and one clever theory potentially uncovers a hidden connection between Batman and the Joker. The second film in Nolan’s Dark Knight trilogy sees Batman finally face his nemesis, the Joker. Heath Ledger’s turn as the Clown Prince of Crime is unforgettable, serving as a perfect antithesis to The Dark Knight‘s Batman.

The film follows Batman as he attempts to apprehend the Joker, who is on his own crusade to seed chaos in Gotham City. As the Joker works to unravel the threads holding the city together, Batman discovers more about the nature of heroism and his willingness to save Gotham at any cost. The hero and villain’s opposing goals ultimately set them against one another, marking the beginning of one of DC’s most iconic pairings.

However, one especially clever theory about The Dark Knight hints at a stronger connection between Batman and the Joker. The theory suggests that the pair are secretly brothers, with the Joker being the illegitimate son of Thomas Wayne. Though this plot point was later touched upon on 2019’s Joker, Nolan’s movie may have secretly used it over a decade prior.

The Dark Knight Repeatedly Hints That Batman & Joker Are Brothers

Heath Ledger as the Joker and Christian Bale as Batman in The Dark Knight (2008)

Watching the Joker carefully and considering his somewhat cryptic clues about his past reveal clear issues with his father. After a well-dressed man stands up to him, he reacts emotionally by saying: “you remind me of my father. I hated my father.” This suggests that a) Joker’s father is dead, and b) that either the man’s attire or attitude triggered this response. In the Dark Knight trilogy, the previous well-dressed man to stand up to a criminal was none other than Thomas Wayne, who is indeed dead. (We’re pretty sure, at least.)

Later in the film, when the Joker gets a chance to talk directly with Batman, he insists in earnest that “they’ll cast you out” when they no longer need you“. It’s an interesting exchange in which the Joker exudes something like sympathy for the hero. Connecting those dots creates the theory that the Joker himself was once cast out after no longer being needed. Perhaps a half-brother being sent away upon Bruce’s arrival? It would explain why Joker hates Thomas Wayne and why he insists he and Batman are alike.

Maybe there’s truth to the theory, or maybe it’s wishful thinking. Still, thinking that The Dark Knight had a hidden meaning all along, intending eventually reveal that Ledger’s Joker and Bale’s Batman were brothers is something that will likely keep us up at night. As ludicrous as it sounds, it’s plausible, and it would be a brilliant way to explain Batman and Joker’s connection.